:root {
  --primary-bg: #10141a;
  --secondary-bg: #1a2027;
  --accent-color: #2979ff;
  --text-color: #e0e6ed;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 2rem;
  --font-base: 'Arial', sans-serif;
  --footer-height: 3rem;
}

html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background-color: var(--primary-bg);
  color: var(--text-color);
  font-family: var(--font-base);
}

/* === App Layout === */
.app-header {
  grid-area: header;
  background-color: var(--secondary-bg);
  padding: var(--spacing-md);
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid #2c3440;
}

.sidebar {
  grid-area: sidebar;
  background-color: var(--secondary-bg);
  padding: var(--spacing-lg) var(--spacing-md);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  border-right: 1px solid #2c3440;
}

.chart-panel {
  grid-area: main;
  padding: var(--spacing-md);
  display: flex;
  flex-direction: column;
  justify-content: flex-start;
  align-items: stretch;
}

.app-footer {
  grid-area: footer;
  background-color: var(--secondary-bg);
  height: var(--footer-height);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  border-top: 1px solid #2c3440;
}

body {
  display: grid;
  grid-template-areas:
    "header header"
    "sidebar main"
    "footer footer";
  grid-template-columns: 250px 1fr;
  grid-template-rows: auto 1fr var(--footer-height);
  min-height: 100vh;
}

/* === Responsive Design === */
@media (max-width: 768px) {
  body {
    grid-template-areas:
      "header"
      "main"
      "sidebar"
      "footer";
    grid-template-columns: 1fr;
    grid-template-rows: auto 1fr auto var(--footer-height);
  }

  .sidebar {
    flex-direction: row;
    justify-content: space-around;
    border-right: none;
    border-top: 1px solid #2c3440;
    padding: var(--spacing-md);
  }

  .chart-panel {
    padding: var(--spacing-sm);
  }
}

/* === Footer Copyright === */
.app-footer::after {
  content: "© 2026 Donau2Space.de";
  color: var(--text-color);
}